‘77 C20
Gen 1 SBC
4L80E
Dual tank with in-tank fuel pumps & Pollack valve.
Dual C4 controlled radiator fans.
Electric water pump.
Dominator ECU
7” Digital Dash

I’m having some strange output voltage issues on J2B. I first noticed something odd when I was testing radiator fans, they still operate and modulate, but at half the RPM they should at 90% duty cycle. Then I noticed outputs won’t energize the relays.

Battery voltage @ 12.1 VDC during testing.
Water pump output @ 7.04 VDC - J2B-B4
CCVP enable @ 7.6VDC - J2B-B2

The fuel pump and changeover valve alternate output voltage when the digital dash switch is toggled.
Fuel Pump Driver @ 6.94VDC - J2B-B24 - changes to 12.07VDC when toggled
Fuel Pump Pass @ 12.1VDC - J2B-B25 - changes to 7.07VDC when toggled
Fuel Tank Changeover @ 7.39VDC - J2B-B1 - changes to 12.06VDC when toggled

Holley had me send the ECU back to them for warranty with this response:
“Due to open load detection circuitry, when one measures an output with a VOM that is not active AND with no load, the VOM may read a moderate voltage level. There is not enough power potential to cause any type of output activation and is normal.”

I haven’t heard of this before. I have done all the checks that have been recommended and am a little stumped. Thanks for any help. Peter